Safety device for pneumatic hammers



Patented June 27, 1933 PATENTl OFFICE CHARLES F. HELlx/IS, F ROANOKE, VIRGINIA, ASSIGNOR OF ONE-THIRD TO JOI-IN IP. HELMS, (F ROANOKE, VIRGINIA, AND ONE-THIRD T0 LEONARD V. HALE, OF SALEM,

VIRGINIA SAFETY DEVICE FOR PNEUMATIC HAMMERS Application filed June 2, 1932. Serial No. 615,012.

is retained securely in place in the barrel of the machine, accidental discharge being effectually prevented thereby, while the speedy and easy removal of the tool when desired is permitted. l

A further obj ect of the invention is to supply a safety device for the purpose stated such that it can be applied to standard makes of pneumatic hammer or percussion machine that use inserted bits.

A further obj ect is to supply a safety device for the purpose stated such that the application thereof to a standard pneumatic hammer or the like can be readily effected without weakening any part thereof or changing in any way its size or affecting its proper balance.

A further objectis to supply a safety device for the stated purpose so constructed that it can be applied to` any standard pneumatic machine quickly and inexpensively and with the aid only of ordinary machine shop equipment (such as a standard lathe and shaper) and Vby the use only of materials readily obtainable and at little cost.

A further object is to supply a safety device for the purpose stated, which is made a permanent part of the machine and therefore cannot be accidentally misplaced.

A further object is to supply a safety device for the purpose stated, which has no projecting parts, all its parts'being flush with or within the circumference of the barrel of the machine.

Other objects and advantages of the invention will be apparent from the following description, in which reference is made tothe accompanying drawing, wherein a preferred embodiment of the invention is illustrated ment made according to this invention applied thereto;

Fig. 2 is a vertical longitudinal section on a larger scale (approximately full size) of the forward end of the barrel of said hammer; K

Fig. 3 is a cross-section on line 3-3 of Fig. 2;

Fig.4 is a horizontal section; F ig. 5 is an end elevation, therivet set being removed; and

Fig. 6 is a detail view showing the safety device in perspective.

The machine illustrated in the drawing is a pneumatic hammer of standard make designed 'specially for riveting; said machine comprising a barrel 10, piston or hammer member 11, handle 12, trigger control 13 and other parts, all of the usual construction, except for modications in the barrel member at its forward end, as hereinafter described.

In the drawing, the hammer is shown in conjunction with a rivet set of the usual construction, having a shank 14, which fits for reciprocating movement within the bore of barrel 10, and a head 15 of larger diameter than the shank. Y

In the embodiment of the invention here illustrated the retaining device or safety appliance comprises as its principal parts a detent carrier consisting of al flat spring 17 (Fig. 6) curved in the arc of a circle and preferably of a length somewhat more than 180 degrees, towhich, about midway on its inner side, is attached a detent in the form of a lug or ydog 18, the attachment being effected by means of screw-s 19, or otherwise. One end of the spring band 17 is formed into a loop or eye, as shown at 20, through which passes a pivot screw 21, thus constituting a hinge connection by which the spring band or detent carrier is attached permanently to the barrel and may be snapped quickly into gripping engagement around the surface of the barrel and thereby position the detent to lock or retain the rivet set or other tool in operative position, or may be moved out of operative position (as shown in dotted lines in Fig. 3) to release the tool and permit removal and replacement thereof.

To adapt this retaining device to a. pneumatic hammer such as shown in the drawing, the following changes are made:

First-A. circumferential groove or recess 23 is .made in shank 14; of the rivet set or other tool, the depth of the groove being suiiicient for the effective entrance of the detent 18, which thereby prevents the rivet set from fiying off, and the width of the groove being suiiicient to permit the predetermined length of working stroke of the rivet set or other tool. As groove 23 extends entirely around shank 14, the rivet set is free to revolve within the barrel 10.

Second-A shallow groove or recess 25 is made in the exterior of barrel 10, the width and depth thereof being such that spring 17 fits snugly the outer surface of the barrel in said groove, so that when the retaining device is in active vposition it is flush with the surface of the barrel. Groove 25 is slightly deepened at 26, just beneath the free end of spring 17 (Figs. 3 and 5) to facilitate engagement of the end of said spring by the operators finger, or an implement, for the purpose of snapping said spring out of its holding position to permit insertion or removal of a tool.

Third-The barrel 10 is slotted or recessed at 27 (Fig. 3) to form an opening for the entrance of detent or lug 18 into the interior of the barrel. Said opening 27 is of a size and shape, as shown in Fig. 3, such as to permit the entrance and withdrawal of lug 18 when spring band 17 is swung on its hinge (see gewi-In order to attach the safety device pivotally to the hammer, the barrel 10 is milled out at 28 (Fig. 4) and groove or recess 25 is deepened at that part of its circumference, thus forming a, shoulder 29, which is drilled for the passage of pivot screw 21. The latter, after passing through the eye or loop 2O of spring band 17, is tapped into barrel 10, as shown in Fig. 4.

The above described operations can be readily performed .upon any standard make of pneumatic hammer, at small cost and by means of ordinary machine shop equipment; and they do not appreciably weaken the machine or in any manner effect its balance or otherwise lessen its efficiency. The safety device itself is of exceedingly simple construction, easily made, and composed of materials that are inexpensive and readily obtainable, namely, a small spring to constitute the detent carrier 17 a. small piece of tool steel to constitute the detent 18, and several screws 19, 19 and 21.

Other advantages of the invention are that nothing is added to the standard pneumatic hammer or percussion aparatus than can interfere with the handling and operation thereof; the rivet set (also called the snap),

or other tool, is free to be thrust out of the barrel to a limited extent in the act of snapping down rivets and also is free to revolve; there are no exposed parts such as can be accidentally displaced or are in the way; and the safety device, while effectually preventing accidental discharge of the tool, permits the speedy and easy removal and insertion thereof.

What is claimed is- 1. In a. percussion apparatus, the combination of a barrel adapted to receive at one end thereof a rivet set or other tool; a detent carrier consisting of a spring of a curvature approximating the perimeter of the barrel and of a length in excess of half-way around the barrel; a detent on said carrier about midway of its length; a hinge connection attaching said carrier at one end to the barrel and on which said carrier may be swung to either a locking position in which it makes yielding gripping engagement with the barrel more than half-way about the same and thereby holds the carrier in locking position with the detent thereon projecting through an opening in the wall of the barrel into engagement with an inserted tool to retain the latter in place, or to a releasing position with carrier sprung out of engagement with the barrel and the detent on the carrier disengaged from the tool.

2. In a percussion apparatus, the combination of a barrel adapted to receive at one end thereof'a rivet set or other tool and having a relatively shallow groove extending more than half-way around the exterior surface thereof; a detent carrier consisting of a spring of a curvature approximating the surface at the bottom of said groove and of a length in excess of half-way around the barrel; a detent on said carrier about midway of its length; a hinge connection attaching said carrier at one end to the barrel and on which said carrier may be swung to either a locking position in which it occupies said groove and makes yielding gripping engagement with the barrel more than half-way about the same and thereby holds the carrier in locking position with the detent thereon pro'ecting through an opening in the wall of the arrel into engagement with an inserted tool to retain the latter in place, or to a releasing position with the carrier sprung out of engagement with the barrel and the detent on the carrier disengaged from the tool.

3. In a percussion apparatus, the combination of a barrel adapted to receive at one end thereof a rivet set or other tool and having a relatively shallow groove extending more than half-way around the exterior surface thereof; a detent carrier consisting of a spring band of a width and thickness approximating the width and depth of said groove, of a curvature approximating the surface at the bottom of said groove and of a length in excess of half-Way around the barrel; a detent on said carrier about mid- Way of its length; a hinge connection attaching said carrier at one end to the barrel in said groove and on which hinge connection said carrier may be swung to either a looking position in which it occupies said groove and makes yielding gripping engagement with the barrel more than half-Way about the same and thereby holds the carrier in locking posispecification.

CHARLES F. HELMS. 

